In the related art, surgery, such as neurosurgery, for example, brain tumors are typically excised through an open craniotomy approach guided by imaging. The data collected in these solutions typically consists of computerized tomography (CT) scans with an associated contrast agent, such as iodinated contrast agent, as well as MRI scans with an associated contrast agent, such as gadolinium contrast agent. Also, optical imaging is often used in the form of a microscope to differentiate the boundaries of the tumor from healthy tissue, known as the peripheral zone. Tracking of instruments relative to the patient and the associated imaging data is also often achieved by way of external hardware systems such as mechanical arms, radiofrequency, or optical tracking devices. As a set, these devices are commonly referred to as surgical navigation systems and are often cumbersome and provide inaccurate tracking.
Port-based surgery is a minimally invasive surgical technique where a port is introduced to access a surgical region of interest using surgical tools. Unlike other minimally invasive techniques, such as laparoscopic techniques, a port diameter is larger than a tool diameter. Hence, the tissue region of interest is visible through the port, wherein exposed tissue in a region of interest, at a depth few centimetres below the skin surface, is accessible through a narrow corridor in the port.
Several related art problems generally preclude or impair the ability to perform port-based navigation in an intra-operative setting. For example, the position of the port axis relative to a typical tracking device (TD) is a free and uncontrolled parameter that prohibits the determination of access port orientation. Further, the limited access which is available, due to the required equipment for the procedure, causes indirect access port tracking to be impractical and unfeasible. Also, the requirement for angulation of the access port to access many areas within the brain during a procedure makes navigation of the access port a difficult and challenging problem that has not yet been addressed.
Additionally, the climbing costs of healthcare, coupled with alarming rates of malpractice suits, have highlighted the need for an efficient and effective method of surgical training in the related art, e.g., in relation to neurosurgery and cardiovascular surgery. Gross malpractice payments aside, surgical errors increase hospitalization time and adversely affect the health of patients, resulting in death or injury. The majority of these errors have been attributed to lack of skill and experience on the part of medical personnel. A number of simulation tools have been used in the related art, but have faced challenges in optimally training surgeons.
For instance, U.S. Patent Publication No. 20150347682 involves simulation by acquiring 2-D images, optionally including using X-rays, to generate 3-D or 4-D imaging. U.S. Patent Publication No. 20150347682 involves simulation by acquiring medical imaging data encoded in a standard video format. U.S. Patent Publication No. 20150086955 involves simulation of a tissue model configured so that one or more of the layers are in the form of a lattice structure rather than fully solid layers using silicone with 3-D printing. However, these related art tissue simulations are insufficiently realistic for optimally training surgeons.
In another example, U.S. Patent Publication No. 20140378995 involves a simulator having a surgeon's console with a software suite to simulate a surgical instrument and a training environment. This related art simulator has training exercises corresponding to difficulty levels, wherein, upon completion of a task, the user receives a report describing performance metrics and a composite score is calculated from these metrics in relation to only the user's own performance.
In addition, in the related art, phantoms or simulators are used in surgical training. Certain sub-anatomical features present a development manufacturing challenge in the related art. For example, brain ventricles are negative spaces within the brain that allow cerebral spinal fluid (CSF) to circulate and nourish the brain and provide protection against compression. A number of related art methods, e.g., as described in U.S. Pat. No. 9,202,389 to Okano (limited to simulated blood vessels), for preparing these structures have experienced many challenges, such as a related art method of creating voids or negative spaces, wherein balloons are inflated within a liquid hydrogel and subsequently cooled. After one freeze-thaw cycle (FTC), the balloon is removed from the hydrogel, whereby a scar is formed on the surface, thereby necessitating post-processing, such as back-filling with water and removal of air pockets that develop. Further, use of a polyvinyl alcohol (PVA) in the related art comprises using PVA having a molecular weight in a range of less than 3,500 vinyl alcohol units. Related art simulations also use silica particles for preventing stickiness of the low molecular weights PVA; however, the silica particles also impart an unrealistic texture to the simulation.
Another challenge in the related art involves the use of dimethyl sulfoxide (DMSO) as a solvent in formulated simulated tissue structures. However, the use of DMSO raises a number of safety concerns, such as toxicity and volatility. In terms of toxicity, although DMSO has been generally regarded as a non-toxic solvent with a median lethal dose higher than ethanol, harm to the eye, headaches, burning and itching of skin and strong allergic reactions have been experienced. Further, DMSO may cause contaminants, toxins, and medicines to be absorbed through the skin, with unexpected effects, such as acting as a developmental neurotoxin and causing genotoxicity, e.g., whereby the genetic infrastructure of cells is damaged, whereby mutations may be caused, and whereby cancer may develop. In terms of volatility, DMSO may be harmful if inhaled, causing respiratory tract infections. Furthermore, DMSO, as a solvent, has potentially damaging effects on contact with polymeric component parts in medical equipment, thereby leading to damage and loss of hardware as well.
Accordingly, challenges experienced in the related art include inaccuracy in training surgeons to perform neurosurgery or cardiovascular surgery, especially in relation to situations involving real-time registration of a surgical trajectory, wherein unique characteristics of a particular tissue types or sub-types, e.g., cerebral tissue or cardiovascular tissue, is significant. Also, surgical training involving simulated microvascular structures is particularly challenging for at least that realistic simulated microvascular strut cures are difficult to fabricate in the related art. For example, many related art simulated blood vessels are formed from silicone and rubber which have properties that are highly dissimilar to those of actual anatomic structures. Related art methods of training in anastomosis typically involve placing a simulated blood vessel in a flat disposition flat on a horizontal surface and performing a training task. Therefore, a need exists for improved simulated tissue products and methods that provide a realistic representation of anatomical structures without the use adverse fillers or adverse solvents for use with a surgery simulator.